Radial and thickness control via biased multi-port injection settings

ABSTRACT

A gas distribution system is disclosed in order to obtain better film uniformity on a substrate in a cross-flow reactor. The better film uniformity may be achieved by an asymmetric bias on individual injection ports of the gas distribution system. The gas distribution may allow for varied tunability of the film properties.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a continuation of U.S. application Ser. No.15/450,199 filed on Mar. 6, 2017, entitled “Radial and Thickness Controlvia Biased Multi-port Injection Settings,” which claims priority to U.S.Provisional Patent Application No. 62/312,951, entitled “Radial andThickness Control via Biased Multi-port Injection Settings” and filed onMar. 24, 2016, the contents of which are hereby incorporated herein byreference to the extent such contents do not conflict with the presentdisclosure.

FIELD OF INVENTION

The invention relates to a reaction system for processing semiconductorsubstrates. Specifically, the invention relates to biasing a gasdistribution apparatus that results in improved film uniformity forsubstrates in the reaction system.

BACKGROUND OF THE DISCLOSURE

In a cross-flow reaction system, deposition of a film may occur whengases flow across a surface of the substrate. These deposition processesmay result in a greater deposition of film in a center of a substrate incomparison to an edge of the substrate. In addition, it may be possiblethat a chemical composition of a film may differ in the center of thesubstrate compared to the edge of the substrate.

An uneven distribution of a deposited film's thickness and chemicalcomposition may prove to be problematic in the processing ofsemiconductor substrates. The layer may have within wafer device issuesdue to non-uniform film thickness and composition, causing unevenness indevice performance (such as mobility, etc.) on the same substrate.

As a result, a need exists for a system that distributes gas in a mannerthat improves film uniformity.

SUMMARY OF THE DISCLOSURE

A method for performing an asymmetric biasing of precursor gas injectionis disclosed. The method comprises: providing a reaction chamber, thereaction chamber holding a substrate to be processed; providing a firstmultiple port injector assembly, the first multiple port injectorassembly comprising a first plurality of individual port injectors forproviding a first gas from a first gas source to the substrate;providing a second multiple port injector assembly, the second multipleport injector assembly comprising a second plurality of individual portinjectors for providing a second gas from a second gas source to thesubstrate; flowing the first gas onto the substrate with the firstmultiple port injector assembly, wherein the first multiple portinjector assembly has an asymmetric or symmetric bias of the firstplurality of individual port injectors; and flowing the second gas ontothe substrate with the second multiple port injector assembly, whereinthe second multiple port injector assembly has an asymmetric orsymmetric bias of the second plurality of individual port injectors;wherein a substantially uniform distribution of the first gas and thesecond gas across the substrate is achieved; and wherein a reactiontakes place between the first gas and the second gas on the substrate toform a first film.

For purposes of summarizing the invention and the advantages achievedover the prior art, certain objects and advantages of the invention havebeen described herein above. Of course, it is to be understood that notnecessarily all such objects or advantages may be achieved in accordancewith any particular embodiment of the invention. Thus, for example,those skilled in the art will recognize that the invention may beembodied or carried out in a manner that achieves or optimizes oneadvantage or group of advantages as taught or suggested herein withoutnecessarily achieving other objects or advantages as may be taught orsuggested herein.

All of these embodiments are intended to be within the scope of theinvention herein disclosed. These and other embodiments will becomereadily apparent to those skilled in the art from the following detaileddescription of certain embodiments having reference to the attachedfigures, the invention not being limited to any particular embodiment(s)disclosed.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

These and other features, aspects, and advantages of the inventiondisclosed herein are described below with reference to the drawings ofcertain embodiments, which are intended to illustrate and not to limitthe invention.

The patent or application file contains at least one drawing executed incolor. Copies of this patent or patent application publication withcolor drawing(s) will be provided by the Office upon request and paymentof the necessary fee.

FIG. 1 illustrates a gas injection system in accordance with at leastone embodiment of the invention.

FIG. 2 illustrates a graph of thickness in accordance with at least oneembodiment of the invention.

FIG. 3 illustrates a graph of composition in accordance with at leastone embodiment of the invention.

It will be appreciated that elements in the figures are illustrated forsimplicity and clarity and have not necessarily been drawn to scale. Forexample, the dimensions of some of the elements in the figures may beexaggerated relative to other elements to help improve understanding ofillustrated embodiments of the present disclosure.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Although certain embodiments and examples are disclosed below, it willbe understood by those in the art that the invention extends beyond thespecifically disclosed embodiments and/or uses of the invention andobvious modifications and equivalents thereof. Thus, it is intended thatthe scope of the invention disclosed should not be limited by theparticular disclosed embodiments described below.

Embodiments of the invention are directed to creating a more uniformfilm on a substrate in a cross-flow reactor. Issues of uniformitybetween a center and an edge of a substrate are common in deposition ofmulti-component group IV epitaxial layers, such as Si:P, SiC:P, Si:B,SiGe:C, SiGe:P, Ge:P, Ge:B, GeSn, GeSn:B, GeSn:P, and SiGeSn, forexample. Embodiments of the invention are directed to formation of thesemulti-component group IV epitaxial layers, and are just as applicable toelemental films (such as Si, Ge, Ga, and As), binary films (such asSi_(1-x)C_(x), SiGe, GeSn, SiSn), ternary films (such as SiGeC andSiGeSn), and quaternary films (such as SiGeSnC and SiGeCP). These filmsmay be either doped (p-type or n-type) or undoped (such as undoped SiGe,for example). Embodiments of the invention are directed to creating auniform thickness of the film, as well as a uniform chemicalconcentration across the substrate. Embodiments of the invention may bedirected to processes that are selective or non-selective. Selectiveprocesses may comprise a selective epitaxial growth (SEG) process, aco-flow process, or a cyclic deposition and etching (CDE) process.

FIG. 1 illustrates a reaction system 10 in accordance with at least oneembodiment of the invention. The reaction system 10 may be an epitaxydeposition tool, such as the Intrepid from ASM International N.V. Anexample of the reaction system 10 may be disclosed in U.S. patentapplication Ser. No. 14/218,690, assigned to ASM IP Holding B.V., whichis incorporated herein by reference.

The reaction system 10 may comprise a first multi-port injector (MPI)100 and a second multi-port injector (MPI) 200. The first MPI 100 maycomprise a first plurality of individual injection ports 101-105, whilea second MPI 200 may comprise a second plurality of individual injectorports 201-205. The individual injector ports 101-105 and the individualinjector ports 201-205 may comprise a BMW series metering valvemanufactured by Swagelok® and a brushless DC motor manufactured byHanBay Inc., for example. In addition, injector ports may be controlledby mass flow controllers (MFCs) manufactured by Horiba or MKSInstruments. The first MPI 100 and the second MPI 200 may be disposed ina close spatial relationship or separated spatially. The first MPI 100and the second MPI 200 are not limited to five individual injector portsand may have more or less than five individual injector ports dependingon the application. For example, the number of individual injector portsmay range from 1 to 15, from 3 to 10, or from 5 to 8 depending on theapplication.

Within the reaction system 10, a substrate 120 may be rotating in eithera counterclockwise (as pictured) or in a clockwise manner. The clockwiseor counterclockwise rotation may take place at a rate of 5 rpm to 120rpm, or preferably between 10 rpm and 40 rpm. The rate of rotation isnot limited to the ranges below and may exceed 120 rpm or be below 5rpm. An additional MPI and individual injector ports may be disposedwithin the same reaction chamber in order to allow injection of a secondgas onto the substrate 120.

For the formation of multi-component group IV epitaxial layers, such mayrequire flow of multiple gases. Flow of a first gas may be a siliconsource, such as dichlorosilane (DCS), silane (SiH₄), disilane (Si₂H₆),trisilane (Si₃H₈), or trichlorosilane (TCS). Flow of a second gas may bea dopant or alloy precursor gas, for example. An example of a dopant oralloy precursor gas may comprise at least one of: phosphine (PH₃),germane (GeH₄), digermane (Ge₂H₆), diborane (B₂H₆), methane (CH₄), tinchloride (SnCl₄), arsine (AsH₃), or mono-methylsilane (MMS). The dopantor alloy precursor gas may comprise either n-type or p-type dopants. Inaddition, HCl, chlorine (Cl₂), hydrogen (H₂), or nitrogen (N₂) may beadded to either the first gas or the second gas for selectivity anddilution purposes. A third gas maybe used for etching in CDE processes.The third gas may be HCl or chlorine (Cl₂). Gas flows may be symmetricor asymmetric depending on the desired process tunability.

In order to avoid the center-to-edge uniformity issues, at least oneembodiment of the invention may relate to an asymmetric biasing of theindividual injector ports 101-105. An asymmetric biasing of theindividual injector ports may involve allowing different flow rates forthe individual injector ports 101-105. For example, the individualinjector ports 101-102 may be configured to allow flow of a dopant gas,while the other individual injector ports 103-105 may be configured toflow no gas at all. The flow of gas through the individual injectorports 101-105 can be varied by a number of turns on a valve for theindividual injector ports 101-105. In addition, injector ports may becontrolled by mass flow controllers (MFCs) manufactured by, for example,Horiba or MKS Instruments.

A software program may be configured to control the flow through theindividual injector ports 101-105. The software program may dictate howlong the individual injector ports 101-105 are open as well as theextent to which the individual injector ports 101-105 are open.

In accordance with at least one embodiment of the invention, a dopedfilm (such as a Si:P film) may be formed. To do so, the first MPI 100may flow dichlorosilane (DCS) onto a substrate. The flow may take placeat a reactor pressure ranging between 1 torr and 760 torr, preferablybetween 100 torr and 500 torr. The flow may take place at a reactortemperature ranging between 250° C. and 1100° C., preferably between350° C. and 800° C. The flow may have a duration that depends on adesired thickness, growth rate, and film thickness. In accordance withat least one embodiment, an asymmetric biasing of the individualinjector ports may take place such that individual injector ports101-102 may flow the DCS, while the other individual injector ports103-105 do not flow any DCS. In accordance with at least one embodiment,an asymmetric biasing of the individual injector ports may result suchthat individual injector ports 101, 102, and 105 do not flow gas, whileindividual injector ports 103 and 104 flow gas, or such that individualinjector ports 101 and 105 do not flow gas, while individual injectorports 102, 103, and 104 flow gas.

The second MPI 200 then may flow phosphine onto the substrate. The flowmay take place at a reactor pressure ranging between 1 torr and 760torr, preferably between 100 torr and 500 torr. The flow may take placeat a reactor temperature ranging between 250° C. and 1100° C.,preferably between 350° C. and 800° C. The flow may have a duration thatdepends on a desired thickness, growth rate, and film thickness. Inaccordance with at least one embodiment, an asymmetric biasing of theindividual injector ports may take place such that individual injectorports 201-202 may flow the phosphine, while the other individualinjector ports 203-205 do not flow any phosphine. In accordance with atleast one embodiment, an asymmetric biasing of the individual injectorports may result such that individual injector ports 201, 202, and 205do not flow gas, while individual injector ports 203 and 204 flow gas,or such that individual injector ports 201 and 205 do not flow gas,while individual injector ports 202, 203, and 204 flow gas.

The asymmetric biasing may indicate a more uniform distribution ofphosphine applied to the substrate. The asymmetric biasing may allow foran improved tunability to the process, thus allowing for versatility inthe films deposited. FIG. 2 illustrates a set of results illustratingthickness as a function of position from a center of the wafer usingasymmetric flow configurations. Different lines on the graph representdifferent asymmetric conditions. The asymmetric biasing may lead to athickness profile to be tuned from a frown profile (as seen in ConditionB) to a smile profile (as seen in Condition A), thus providing a widerange of tunability for thickness.

FIG. 3 illustrates a set of results illustrating composition as afunction of position from a center of the wafer using asymmetric flowconfigurations. Similar to FIG. 2, different lines on the graphrepresent different asymmetric conditions. The asymmetric biasing maylead to a phosphorus composition profile to be tuned from a frownprofile (as seen in Condition E) to a smile profile (as seen inConditions D and F), thus providing a wide range of tunability forconcentration.

In accordance with at least one embodiment of the invention, thereaction system 10 may be used to form multi-layer film stacks, whichmay comprise alternating layers of silicon (Si) and silicon germanium(SiGe). These films may be undoped.

In accordance with at least one embodiment of the invention, thereaction system may also be used in CDE. In such an arrangement, aprocess may comprise of alternating deposition and etching steps. Inetching step, chlorine (Cl₂) gas may be flowed. The flow may take placeat a reactor pressure ranging between 1 torr and 760 torr, preferablybetween 10 torr and 200 torr. The flow may take place at a reactortemperature ranging between 250° C. and 1100° C., preferably between350° C. and 800° C.

A biasing of the individual injector ports may be arranged as needed. Inaccordance with one embodiment of the invention, an asymmetric biasingof the individual injector ports may take place such that individualinjector ports 201-202 flow chlorine, while the other individualinjector ports 203-205 do not flow chlorine. In accordance with at leastone embodiment, an asymmetric biasing of the individual injector portsmay result such that individual injector ports 201, 202, and 205 do notflow gas, while individual injector ports 203 and 204 flow gas. Inanother embodiment, a biasing may take place such that individualinjector ports 201 and 205 do not flow gas, while individual injectorports 202, 203, and 204 flow gas. The deposition and etching may berepeated several cycles ranging between 0 cycle to 100 cycles,preferably between 0 and 50 cycles.

In order to form these film stacks, the first MPI 100 may be configuredto flow a silicon source (such as dichlorosilane (DCS) or silane) andhydrochloric acid (HCl). The flow may take place at a reactor pressureranging between 1 torr and 200 torr, preferably between 5 torr and 60torr. The flow may take place at a reactor temperature ranging between200° C. and 1000° C., preferably between 300° C. and 900° C. The flowmay have a duration that depends on a desired composition and thicknessof the layer.

An asymmetric biasing of the individual injector ports may take placesuch that individual injector ports 101-102 may flow the DCS, while theother individual injector ports 103-105 do not flow any DCS. Otherasymmetric biasing conditions may be possible depending on a desiredprofile. The first multi-port injector 100 may also be connected to asource of HCl. The individual injector ports 101-105 may be configuredsuch that particular injector ports may flow DCS, while others flow HCl.

The second MPI 200 may be configured to flow a germanium source, such asgermane (GeH₄) or digermane. The flow may take place at a reactorpressure ranging between 1 torr and 200 torr, preferably between 5 torrand 60 torr. The flow may take place at a reactor temperature rangingbetween 200° C. and 1000° C., preferably between 300° C. and 900° C. Theflow may have a duration that depends on a desired composition andthickness of the layer. An asymmetric biasing of the individual injectorports may take place such that individual injector ports 201-202 mayflow the GeH₄, while the other individual injector ports 203-205 do notflow any GeH₄. Other asymmetric biasing conditions may be possibledepending on a desired profile.

In accordance with at least one embodiment of the invention, thereaction system 10 may be used to form multi-layer film stacks, whichmay comprise alternating layers of germanium (Ge) and germanium tin(GeSn). These film stacks may be used in applications such as stressorsfor logic devices.

In order to form these film stacks, the first MPI 100 may be configuredto flow a tin source (such as tin chloride (SnCl₄) or tin hydride) andhydrochloric acid (HCl). The flow may take place at a reactor pressureranging between 1 torr and 760 torr, preferably between 500 torr and 760torr. The flow may take place at a reactor temperature ranging between100° C. and 800° C., preferably between 150° C. and 500° C. The flowduration depends on the desired composition and thickness of the layer.An asymmetric biasing of the individual injector ports may take placesuch that individual injector ports 101-102 may flow the tin chloride,while the other individual injector ports 103-105 do not flow any tinchloride. The first multi-port injector 100 may also be connected to asource of HCl. The individual injector ports 101-105 may be configuredsuch that particular injector ports may flow tin chloride, while othersflow HCl.

The second MPI 200 may be configured to flow a germanium source (such asgermane (GeH₄) or digermane). The flow may take place at a reactorpressure ranging between 1 torr and 760 torr, preferably between 500torr and 760 torr. The flow may take place at a reactor temperatureranging between 100° C. and 800° C., preferably between 150° C. and 500°C. The flow duration depends on the desired composition and thickness ofthe layer. An asymmetric biasing of the individual injector ports maytake place such that individual injector ports 201-202 may flow thegermane, while the other individual injector ports 203-205 do not flowany germane.

It is to be understood that the configurations and/or approachesdescribed herein are exemplary in nature, and that these specificembodiments or examples are not to be considered in a limiting sense,because numerous variations are possible. The specific routines ormethods described herein may represent one or more of any number ofprocessing strategies. Thus, the various acts illustrated may beperformed in the sequence illustrated, in other sequences, or omitted insome cases.

The subject matter of the present disclosure includes all novel andnonobvious combinations and subcombinations of the various processes,systems, and configurations, and other features, functions, acts, and/orproperties disclosed herein, as well as any and all equivalents thereof.

What is claimed is:
 1. A process for forming a film on a substrate,comprising: providing a reaction chamber, the reaction chamber holding asubstrate to be processed; providing a first multiple port injectorassembly, the first multiple port injector assembly comprising a firstplurality of individual port injectors for providing a first gas from afirst gas source to the substrate; providing a second multiple portinjector assembly, the second multiple port injector assembly comprisinga second plurality of individual port injectors for providing a secondgas from a second gas source to the substrate; flowing the first gasonto the substrate with the first multiple port injector assembly; andflowing the second gas onto the substrate with the second multiple portinjector assembly, wherein one or more of: the first multiple portinjector assembly has an asymmetric bias of the first plurality ofindividual port injectors, and the second multiple port injectorassembly has an asymmetric bias of the second plurality of individualport injectors; wherein a substantially uniform distribution of thefirst gas and the second gas across the substrate is achieved; andwherein a reaction takes place between the first gas and the second gason the substrate to form a first film.
 2. The process of claim 1,wherein the first gas comprises at least one of: dichlorosilane (DCS);silane (SiH₄); disilane (Si₂H₆); trisilane (Si₃H₈); trichlorosilane(TCS); hydrochloric acid (HCl); hydrogen (H₂); or nitrogen (N₂).
 3. Theprocess of claim 1, wherein the second gas comprises at least one of:phosphine (PH₃); germane (GeH₄); digermane (Ge₂H₆); diborane (B₂H₆);CH₄; mono-methylsilane (MMS); tin chloride (SnCl₄); tin hydride;hydrochloric acid (HCl); chlorine (Cl₂); hydrogen (H₂); or nitrogen(N₂).
 4. The process of claim 1, wherein the reaction chamber performs aselective process on the substrate.
 5. The process of claim 4, whereinthe selective process comprises a cyclic deposition and etching (CDE)process.
 6. The process of claim 4, wherein the selective processcomprises a co-flow of the first gas and the second gas.
 7. The processof claim 4, wherein the selective process comprises a selectiveepitaxial growth (SEG) process.
 8. The process of claim 1, wherein thereaction chamber performs a non-selective process on the substrate. 9.The process of claim 1, wherein a pressure of the reaction chamberranges between 1 torr and 760 torr, or between 500 torr and 760 torr.10. The process of claim 1, wherein a temperature of the reactionchamber ranges between 100° C. and 800° C., or between 150° C. and 500°C.
 11. The process of claim 1, wherein the first multiple port injectorassembly has an asymmetric bias of the first plurality of individualport injectors and the asymmetric bias of the first plurality ofindividual port injectors comprises a first number of individual portinjectors flowing the first gas and a second number of individual portinjectors not flowing the first gas.
 12. The process of claim 1, whereinthe second multiple port injector assembly has an asymmetric bias of thesecond plurality of individual port injectors and the asymmetric bias ofthe second plurality of individual port injectors comprises a thirdnumber of individual port injectors flowing the second gas and a fourthnumber of individual port injectors not flowing the second gas.
 13. Aprocess for forming a uniform film on a substrate, comprising: providinga reaction chamber, the reaction chamber holding a substrate to beprocessed; providing a first multiple port injector assembly, the firstmultiple port injector assembly comprising a first plurality ofindividual port injectors for providing a first gas from a first gassource to the substrate; providing a second multiple port injectorassembly, the second multiple port injector assembly comprising a secondplurality of individual port injectors for providing a second gas from asecond gas source to the substrate; flowing the first gas onto thesubstrate with the first multiple port injector assembly, wherein thefirst multiple port injector assembly has an asymmetric bias of thefirst plurality of individual port injectors; and flowing the second gasonto the substrate with the second multiple port injector assembly,wherein the second multiple port injector assembly has a symmetric biasof the second plurality of individual port injectors; wherein asubstantially uniform distribution of the first gas and the second gasacross the substrate is achieved; and wherein a reaction takes placebetween the first gas and the second gas on the substrate to form afirst film.
 14. The process of claim 13, wherein the asymmetric bias ofthe first plurality of individual port injectors comprises a firstnumber of individual port injectors flowing the first gas and a secondnumber of individual port injectors not flowing the first gas.
 15. Areaction system configured to form a uniform film on a substrate,comprising: a reaction chamber configured to hold a substrate to beprocessed; a first multiple port injector assembly, the first multipleport injector assembly comprising a first plurality of individual portinjectors for providing a first gas from a first gas source to thesubstrate, wherein the first multiple port injector assembly has anasymmetric bias of the first plurality of individual port injectors; anda second multiple port injector assembly, the second multiple portinjector assembly comprising a second plurality of individual portinjectors for providing a second gas from a second gas source to thesubstrate, wherein the second multiple port injector assembly has anasymmetric bias of the second plurality of individual port injectors;wherein a substantially uniform distribution of the first gas and thesecond gas across the substrate is achieved; and wherein a reactiontakes place between the first gas and the second gas on the substrate toform a first film.
 16. The reaction system of claim 15, wherein theasymmetric bias of the first plurality of individual port injectorscomprises a first number of individual port injectors flowing the firstgas and a second number of individual port injectors not flowing thefirst gas.
 17. The reaction system of claim 15, wherein the asymmetricbias of the second plurality of individual port injectors comprises athird number of individual port injectors flowing the second gas and afourth number of individual port injectors not flowing the second gas.